The technique of column agglutination technology (CAT) employs an inert matrix and reagents for agglutination with filtration of formed agglutinates by centrifugation providing a visually indicative means for determining whether a reaction has occurred and if so, the grade of the reaction. First invented in the 1980s by LaPierre and associates, tests using CAT technology are now widely used in health care institutions for the rapid and reliable testing of blood samples. Typically, CAT tests comprise an immunodiagnostic test element such as a “bead cassette” or “gel card” with a number of microtubes, each containing a mixture of gel particles of dextran acrylamide and suitable reagents for performing an agglutination-type assay. For example, in the direct Coomb's assay, a patient's red cell suspension is first added to each microtube and after appropriate incubation with anti-human globulin serum (Coomb's reagent), the card is centrifuged. The results of the assay can then be simply ‘read’ from the card.
In recent years, CAT has been streamlined with the introduction of comprehensive platforms that use a variety of different types of sample receptacle that permit visible agglutination reactions to be observed. For example, one such platform is the ID-Micro Typing System® (Ortho-Clinical Diagnostics, Inc.) which is commonly used for blood grouping, antibody screening, antibody identification, phenotyping, and crossmatching of blood. Because the ID-Micro Typing System Gel Test® requires fewer procedural steps, it is easier to perform and more cost effective than other serological methods. Reduced handling also translates into fewer operator-induced errors and a more objective interpretation of results.
Despite these improvements, a major bottleneck for processing gel cards or similar test elements on current immunohematology platforms such as the ID-Micro Typing System® remains the centrifuge, which is programmed to run continuously for each “batch” loaded onto the system, without interruption, until the batch spin has been completed.
Information relevant to attempts to address this problem can be found in U.S. Pat. Nos. 7,151,973; 7,127,310; 7,072,732; 7,069,097; 6,606,529; 6,490,566; 5,890,134; 5,865,718; 5,826,236; 5,737,728; 5,260,868 and U.S. Publication Nos. US 2005/0004828; US 2004/0074825 and US 2003/0064872. Each one of these references suffers, however, from one or more of the following disadvantages: the references fail to remedy the rate-limiting centrifugation step and also fail to describe a procedure that could improve the overall efficiency of batch centrifugation.
For the foregoing reasons, there is an unmet need in the art to improve the throughput of batch centrifugation protocols.